Patch (or microstrip) antennas typically include a flat metal sheet mounted over a larger metal ground plane. The flat metal sheet usually has a rectangular shape, and the metal layers are generally separated using a dielectric spacer. The flat metal sheet has a length and a width that can be optimized to provide a desired input impedance and frequency response. Patch antennas can be configured to provide linear or circular polarization. Patch antennas are popular because of their simple design, low profile, light weight, and low cost. An exemplary patch antenna is shown in FIGS. 1A and 1B.
Additionally, multiple patch antennas on the same printed circuit board may be employed by high gain array antennas, phased array antennas, or holographic metasurface antennas (HMA), in which a beam of radiated waveforms for a radio frequency (RF) signal or microwave frequency signal may be electronically shaped and/or steered by large arrays of antennas. An exemplary HMA antenna and a beam of radiated waveforms is shown in FIGS. 1C and 1D. Historically, the individual antennas are located closely together to shape and steer a beam of radiated waveforms for a provided sinusoidal signal. Unfortunately, signals may be mutually coupled between the antennas because of their close proximity to each other. Improved designs are constantly sought to improve performance and further reduce cost. In view of at least these considerations, the novel inventions disclosed herein were created.